Étude chimique de d’une plante médicinale camerounaise: Angylocalyx Oligophyllus (fabaceae) et évaluation des propriétés biologiques

Abstract

This work presents the chemical and biological studies of the aerial parts of Angylocalyx oligophyllus (Fabaceae). This plant was chosen because of its uses in traditional medicine to treat some eyes infections and diabetes. phytochemical investigation carried out on Angylocalyx oligophyllus led to the isolation and structure elucidation of its chemical constituents using usual chromatographic techniques. From this study, sixteen (16) compounds were isolated and 15 were totally characterized including a new lactam derivative which was named oligoamide. Fifteen other known compounds belong to six categories of natural substances together with: five flavonoids, three pentacyclic triterpenoids, one naturel cyclitol (pinitol), one alkane; four phytosteroids and one sugar. The structural elucidation of these compounds was established by the interpretation of their spectral data and by comparing with authentic samples or literature values when possible. We equally identified fifty (50) compounds by gas chromatography method couple with mass spectrometry With the aim of establishing a link between the chemical composition of this plant and their uses, some extracts and isolated compounds were evaluated in vitro on one hand for their antibacterial, antifungal and antioxidant potentials and on the other hand, for them in vitro inhibitory effect on urease and alphaglucosidase. These two enzymes do not only play a key role in detoxification an organism but are also involved in reducing the sensitivity of antidiabetic drugs before they attain their targets The tests show that the crude extracts from the stem and leaves of Angylocalyx oligophyllus are not toxic to monkey kidney cells but isolated compounds (oligoamide and pinitol) are slightly toxic. The extract of the Angylocalyx oligophyllus stem and leaves showed activities against some Staphylococcus aureus. Oligoamide and pinitol did not show any activity on bacteria strains Only the extract of the A. oligophyllus leave and compounds (oligoamide and pinitol) showed activities on Candida parapsilosis. Oligoamide, pinitol, formononetin, 3’-méthoxydanzein and afromosin exhibited moderate inhibitory on urease. These compound exhibited poor inhibitory of alphaglosidase. The extract of the A. oligophyllus stem, leave and compounds showed activity with radical’s DPPH. Only stem and leaves extracts showed activity with ABTS and no activity for FRAP. We can therefore understand why Angylocalyx oligophyllus is used in traditional pharmacopeia for diabetes treatment